TWI888574B - Polarizing film and elliptical polarizing plate - Google Patents

Abstract

The polarizing film of the present invention is a single polarizing film including a polarizing element layer, wherein the polarizing element layer is a hardened layer of a polymerizable liquid crystal composition including at least one polymerizable liquid crystal compound, and the polarizing film of the present invention satisfies formula (1): 10>A1/A2>2 (1)

[In formula (1), A1 represents the maximum length of the polarizing element layer in the absorption axis direction, and A2 represents the maximum length of the polarizing element layer in the same plane as A1 and in a direction orthogonal to the above absorption axis direction].

Description

Polarizing film and elliptical polarizing plate

The present invention relates to a polarizing film and an elliptical polarizing plate comprising the polarizing film.

Polarizing films including polarizing elements are used in flat panel displays (FPD) by being attached to image display elements such as liquid crystal units or organic EL (Electroluminescence) display elements. Such polarizing films are widely used as polarizing plates having the following structure: a protective layer such as a triacetyl cellulose film is bonded to at least one surface of the polarizing element, and the polarizing element adsorbs and aligns a compound showing dichroism such as iodine or a dichroic dye on a polyvinyl alcohol resin film.

Among them, in an organic EL display device, in order to suppress the decrease in visibility caused by light reflection in the electrode constituting the device or external light reflection, the industry uses the following elliptical polarizing plate, which is a combination of a polarizing film and a phase difference film, and the phase difference film has a retardation axis at an angle different from the absorption axis of the polarizing element constituting the polarizing film (for example, Patent Document 1). [Prior Art Document] [Patent Document]

[Patent Document 1] Japanese Patent Publication No. 2015-163935

[The problem the invention is trying to solve]

In recent years, polarizing films or elliptical polarizing plates are also widely used in flexible image display devices or vehicle-mounted applications, and depending on their applications, they are sometimes required to be used in special shapes. The inventors of the present invention have newly discovered that, for example, when a polarizing film is used in the following shape, the heat resistance of an elliptical polarizing plate including the polarizing film tends to decrease due to the special shape. The above shape is a shape in which the maximum length of the polarizing film in the absorption axis direction and the maximum length in the direction orthogonal thereto differ greatly.

The purpose of the present invention is to provide a polarizing film which exhibits excellent heat resistance when used as an elliptical polarizing plate and has a special shape. [Technical means for solving the problem]

The inventors of the present invention have made intensive research to solve the above-mentioned problems and have completed the present invention. That is, the present invention includes the following aspects. [1] A polarizing film, which is a single polarizing film including a polarizing element layer, wherein the polarizing element layer is a cured layer of a polymerizable liquid crystal composition including at least one polymerizable liquid crystal compound, and the polarizing film satisfies the formula (1): 10＞A1/A2＞2       (1) [In the formula (1), A1 represents the maximum length of the polarizing element layer in the absorption axis direction, and A2 represents the maximum length of the polarizing element layer in the same plane as A1 and in a direction orthogonal to the absorption axis direction]. [2] The polarizing film as described in the above [1], wherein the maximum length A1 of the polarizing element layer in the absorption axis direction is greater than 10 cm and less than 200 cm. [3] The polarizing film described in [1] or [2] above, which satisfies formula (2): -20°≤θ≤20°       (2) [In formula (2), θ represents the angle between the direction of the maximum straight line distance between two points located on the outer periphery of the polarizing element layer when the straight line distance between the two points is the maximum, and the absorption axis direction of the polarizing element layer]. [4] The polarizing film described in any one of [1] to [3] above, which is substantially rectangular. [5] The polarizing film described in [4] above, which satisfies formula (3): -20°≤θ'≤20°      (3) [In formula (3), θ' represents the angle between the long side direction of the substantially rectangular shape and the absorption axis direction of the polarizing element layer]. [6] An elliptical polarizing plate, comprising: a polarizing film as described in any one of [1] to [5] above, and a phase difference layer having a 1/4 wave plate function. [7] A flexible image display device, comprising an elliptical polarizing plate as described in [6] above. [8] The flexible image display device as described in [7] above, further comprising a window and a touch sensor. [Effects of the invention]

According to the present invention, a polarizing film can be provided which exhibits excellent heat resistance when used as an elliptical polarizing plate and has a special shape.

The following is a detailed description of the implementation of the present invention. Furthermore, the scope of the present invention is not limited to the implementation described here, and various modifications can be made within the scope that does not impair the gist of the present invention.

The polarizing film of the present invention is a single polarizing film including a polarizing element layer and satisfies the following formula (1). 10＞A1/A2＞2       (1) [In formula (1), A1 represents the maximum length of the polarizing element layer in the absorption axis direction, and A2 represents the maximum length of the polarizing element layer in the same plane as A1 and in a direction orthogonal to the above absorption axis direction] In the above formula (1), A1 and A2 both represent the size (length) of the polarizing element layer in a specific direction within the polarizing element layer. The above formula (1) indicates that the polarizing film of the present invention has a shape in which A1 is greater than 2 and less than 10 relative to A2, A1 is the maximum length of the polarizing element layer in the absorption axis direction of the polarizing element layer constituting the polarizing film, and A2 is the maximum length of the polarizing element layer in the same plane as A1 and in a direction orthogonal to the absorption axis direction. When A1 and A2 satisfy the relationship of formula (1), the polarizing film is usually slender in the absorption axis direction.

Generally, a polarizing film that satisfies formula (1) and is thin and long in the absorption axis direction is prone to peeling or bulging at the ends of the strip direction. In particular, such phenomena are more likely to occur when exposed to a high temperature environment. However, the polarizing element layer of the polarizing film of the present invention is a cured layer of a polymerizable liquid crystal composition containing at least one polymerizable liquid crystal compound. Therefore, even if the shape satisfies the above formula (1), the heat-resistant effect of suppressing the peeling or bulging of the ends of the strip direction is excellent. In other words, with respect to a polarizing film in which the polarizing element layer is a cured layer of a polymerizable liquid crystal composition comprising at least one polymerizable liquid crystal compound, by controlling the absorption axis direction of the polarizing element layer and the shape of the polarizing film in a manner satisfying formula (1), it is possible to provide a polarizing film having an elongated shape in the absorption axis direction of the polarizing element layer and having excellent heat resistance that is not easily peeled off even when exposed to a high temperature environment. In the polarizing film of the present invention, the ratio (A1/A2) of the maximum length A1 of the polarizing element layer in the absorption axis direction to the maximum length A2 of the polarizing element layer in the same plane as A1 and in a direction orthogonal to the absorption axis direction is preferably 2.5 or more, more preferably 2.8 or more, and further preferably 3 or more. For example, even if it is 4 or more, 5 or more, or 6 or more, good heat resistance can be achieved. From the perspective of easily ensuring higher heat resistance, the value of A1/A2 is preferably 9.5 or less, and more preferably 9 or less.

In one embodiment of the present invention, the polarizing film of the present invention preferably satisfies the following formula (2) in addition to the above formula (1). -20°≤θ≤20°       (2) [In formula (2), θ represents the angle between the direction of the maximum straight line distance between two points located on the outer periphery of the polarizing element layer when the straight line distance between the two points is the maximum and the absorption axis direction of the polarizing element layer] When the polarizing film satisfies the above formula (2), it can be considered that the absorption axis direction of the polarizing element layer constituting the polarizing film and the direction of the maximum straight line distance between two points located on the outer periphery of the polarizing element layer when the straight line distance between the two points is the maximum are in a nearly parallel relationship. When used for applications that may be viewed through sunglasses, such as polarizing films mounted on vehicle dashboards such as speedometers, polarizing films used in image display devices such as smart phones or tablet computers, etc., it is required that the polarizing films have high visibility when viewed through sunglasses. When the polarizing films are arranged in the following manner, they can provide a shape that ensures high visibility through sunglasses and is elongated in the horizontal direction; the arrangement method is to set the absorption axis direction of the polarizing element layer in a manner that satisfies the above-mentioned formulas (1) and (2) according to the relationship with the maximum straight line distance direction in the required shape, thereby making the absorption axis direction substantially horizontal with respect to the viewer's line of sight. The polarizing film is particularly suitable for a situation where the maximum straight line distance direction of the polarizing film is arranged in a direction substantially horizontal to the viewer's line of sight.

When the absorption axis direction of the polarizing film is arranged in a manner that is roughly horizontal to the viewer's line of sight, with respect to the polarizing film that is elongated in the horizontal direction, from the perspective of further improving the visibility when observed through sunglasses, in one embodiment of the present invention, the above-mentioned θ is preferably greater than -18°, more preferably greater than -15°, and further, preferably less than 18°, more preferably less than 15°.

In the present invention, the shape of a single polarizing element film is not particularly limited as long as it satisfies the above formula (1), and may be, for example, a triangle, a rectangle, a trapezoid, a parallelogram or other quadrilateral, a pentagon or more polygon, an ellipse or a part thereof, a gourd shape, or a combination thereof, or any other unspecified shape. With respect to shapes having corners such as triangles, quadrilaterals, and polygons, shapes having some or all of the corners with curvature may be used.

Hereinafter, an example of the polarizing film of the present invention will be described based on the attached drawings. In FIG. 1 which is a schematic top view showing an example of the polarizing film of the present invention, the polarizing film of the present invention is a rectangle. For example, when the absorption axis direction of the polarizing film is the same direction as the long side direction of the rectangle (parallel direction), in formula (1), the maximum length A1 of the polarizing element layer in the absorption axis direction is equivalent to the length of the long side of the rectangle, and the maximum length A2 of the polarizing element layer in the same plane as A1 and in a direction orthogonal to the above-mentioned absorption axis direction is equivalent to the length of the short side of the rectangle. The direction of the maximum straight line distance between two points located on the outer periphery of the polarizing element layer when the straight line distance between the two points is the maximum becomes the diagonal direction of the rectangle, and an angle θ is formed between the diagonal direction and the absorption axis direction.

On the other hand, for example, as shown in FIG2, when the absorption axis direction of the polarizing element layer is the same direction (parallel direction) as the diagonal direction of the rectangle, A1 in formula (1) is equivalent to the length of the diagonal of the rectangle, and A2 is equivalent to the length connecting point a on the lower side of the rectangle and point b on the upper side in a direction orthogonal to the above A1. In this shape, the maximum straight line distance direction is the diagonal direction of the rectangle, and the angle θ between the maximum straight line distance direction and the absorption axis direction is 0°.

FIG3 shows a schematic top view of the triangular polarizing film of the present invention. For example, when the absorption axis direction of the polarizing film is the same direction (parallel direction) as the base direction of the triangle in FIG3 , A1 in formula (1) is equivalent to the length of the base of the triangle, and A2 is equivalent to the length of the height of the triangle in FIG3 . The maximum straight-line distance direction is the hypotenuse direction of the triangle in FIG3 , and an angle θ is formed between the hypotenuse direction and the absorption axis direction. Furthermore, even for a triangular polarizing film having an absorption axis direction in a direction parallel to the base direction, the maximum straight-line distance direction will be different depending on the angles of the two base angles of the triangle, and the angle θ formed by the maximum distance direction and the absorption axis direction will also change accordingly.

FIG4 shows a schematic top view of an elliptical polarizing film of the present invention. For example, when the absorption axis direction of the polarizing film is the same direction (parallel direction) as the long axis direction of the ellipse in FIG4, A1 in formula (1) is equivalent to twice the length of the long radius of the ellipse, and A2 is equivalent to twice the length of the short radius of the ellipse in FIG4. In this shape, the maximum straight line distance direction is the long axis direction of the ellipse, and the angle θ between the maximum straight line distance direction and the absorption axis direction is 0°.

FIG5 shows a schematic top view of the polarizing film of the present invention in the shape of a portion of an ellipse. For example, when the absorption axis direction of the polarizing film is the same direction (parallel direction) as the chord direction of the shape in FIG5 as shown in FIG5, A1 in formula (1) is equivalent to the length of the chord of the above shape, and A2 is equivalent to the length (height of the arc) of the arc connecting the center point a of the above shape and the point b in the direction orthogonal to A1. In this shape, the direction of the maximum straight line distance is the chord direction of the shape shown in FIG5, and the angle θ between the maximum straight line distance direction and the absorption axis direction is 0°.

The size of the polarizing film of the present invention is not particularly limited as long as it satisfies the above formula (1), and can be appropriately determined according to the purpose of the polarizing film. In one embodiment of the present invention, the maximum length A1 of the polarizing element layer forming the polarizing film of the present invention in the absorption axis direction is preferably greater than 10 cm and less than 200 cm. If A1 is within the above range, it is easy to more significantly exert the effect of improving the heat resistance of the polarizing film. The length of A1 is more preferably greater than 30 cm, further preferably greater than 40 cm, and particularly preferably greater than 50 cm, and further, more preferably less than 180 cm, further preferably less than 160 cm, and particularly preferably less than 150 cm.

The maximum length A2 of the polarizing element layer in the polarizing film of the present invention in the same plane as A1 and in a direction orthogonal to the absorption axis direction of the polarizing element layer is preferably greater than 1 cm and less than 100 cm. If A2 is within the above range, the heat resistance improvement effect of the polarizing film can be more significantly exerted. The length of A2 is preferably greater than 3 cm, further preferably greater than 5 cm, particularly preferably greater than 10 cm, and further preferably less than 70 cm, further preferably less than 50 cm, particularly preferably less than 30 cm.

In one embodiment of the present invention, a single polarizing film of the present invention is substantially rectangular. Here, in this specification, the so-called substantially rectangular refers to a substantially rectangular shape, as long as one set of two opposite sides are parallel and another set of two opposite sides are parallel, the whole can be identified as a rectangle, and at least one of the four corners may be blunt or have a curvature.

When the single polarizing film of the present invention is roughly rectangular, the polarizing film preferably satisfies the following formula (3) in addition to the above formula (1) or the above formulas (1) and (2). -20°≤θ'≤20°      (3) [In formula (3), θ' represents the angle between the long side direction of the roughly rectangular shape and the absorption axis direction of the polarizing element layer]

For example, in the polarizing film shown in Figure 1, the angle θ' formed between the long side direction of the roughly rectangular shape and the absorption axis direction of the polarizing element layer is 0°. On the other hand, in the polarizing film shown in Figure 2, the absorption axis direction parallel to the diagonal direction of the roughly rectangular shape forms an angle θ'.

When the substantially rectangular polarizing film satisfies the above formula (3), it can be considered that the absorption axis direction of the polarizing element layer constituting the polarizing film is approximately parallel to the long side direction of the substantially rectangular shape. When the polarizing film is arranged in such a way that the absorption axis direction is substantially horizontal relative to the viewer's line of sight, a rectangular polarizing film that ensures high visibility through sunglasses and is thin and long in the horizontal direction can be provided. The polarizing film is particularly suitable for the case where the long side direction of the polarizing film is arranged in a substantially horizontal direction relative to the viewer's line of sight. When the absorption axis direction of the polarizing film is arranged in a manner that is roughly horizontal to the viewer's line of sight, with respect to the polarizing film that is elongated in the horizontal direction (roughly rectangular), from the perspective of further improving the visibility when observed through sunglasses, in one embodiment of the present invention, the above-mentioned θ' is preferably greater than -15°, more preferably greater than 10°, and further preferably greater than 5°, and is preferably less than 15°, more preferably less than 10°, and further preferably less than 5°.

The polarizing element layer constituting the polarizing film of the present invention is a cured layer of a polymerizable liquid crystal composition containing at least one polymerizable liquid crystal compound. Compared with the film-like polarizing element layer such as the polyvinyl alcohol resin film adsorbed with dichroic pigments which has been widely used as a polarizing element, the polarizing element layer which is a cured layer of a polymerizable liquid crystal composition has an excellent shrinkage suppression effect when exposed to a high temperature environment, and is easy to show higher heat resistance even in a special shape satisfying the above formula (1). Therefore, for example, it is suitable for use in vehicles that are not prone to peeling or bulging of the ends of slender shapes and are easily exposed to harsh environments; or it is suitable for use as a polarizing film for flexible image display devices that require higher durability.

In the present invention, the polymerizable liquid crystal compound (hereinafter also referred to as "polymerizable liquid crystal compound (A)") contained in the polymerizable liquid crystal composition (hereinafter also referred to as "polymerizable liquid crystal composition (A)") that forms the polarizing element layer is a compound having at least one polymerizable group. Here, the so-called polymerizable group refers to a group that can participate in the polymerization reaction by utilizing an active free radical or acid generated by a polymerization initiator. Examples of the polymerizable group possessed by the polymerizable liquid crystal compound (A) include: vinyl, vinyloxy, 1-vinyl chloride, isopropenyl, 4-vinylphenyl, (meth)acryl, ethylene oxide, cyclobutylene oxide, and the like. Among them, free radical polymerizable groups are preferred, (meth)acryl, vinyl, vinyloxy are more preferred, and (meth)acryl is more preferred.

In the present invention, the polymerizable liquid crystal compound (A) is preferably a compound exhibiting lamellar liquid crystal properties. By using a polymerizable liquid crystal compound exhibiting lamellar liquid crystal properties, a polarizing element layer with a higher degree of alignment order can be formed. From the perspective of achieving a higher degree of alignment order, the liquid crystal state exhibited by the polymerizable liquid crystal compound (A) is more preferably a higher-order lamellar phase (higher-order lamellar liquid crystal state). Here, the so-called high-order smectic phase refers to smectic B phase, smectic D phase, smectic E phase, smectic F phase, smectic G phase, smectic H phase, smectic I phase, smectic J phase, smectic K phase and smectic L phase, among which smectic B phase, smectic F phase and smectic I phase are more preferred. The liquid crystal may be a thermotropic liquid crystal or a hydrotropic liquid crystal. From the perspective of being able to control the thickness of a dense film, a thermotropic liquid crystal is preferred. In addition, the polymerizable liquid crystal compound (A) may be a monomer, an oligomer formed by polymerizing a polymerizable group, or a polymer.

The polymerizable liquid crystal compound (A) is not particularly limited as long as it is a liquid crystal compound having at least one polymerizable group, and known polymerizable liquid crystal compounds can be used. As a polymerizable liquid crystal compound exhibiting lamellar liquid crystal properties, for example, the compound represented by the following formula (A-α) (hereinafter, sometimes referred to as "polymerizable liquid crystal compound (A-α)") can be cited. U ¹ -V ¹ -W ¹ -(X ¹ -Y ¹ ) _n -X ² -W ² -V ² -U ² (A-α) [In the formula (A-α), X ¹ and X ² independently represent a divalent aromatic group or a divalent alicyclic alkyl group, wherein the hydrogen atom contained in the divalent aromatic group or the divalent alicyclic alkyl group may be substituted with a halogen atom, an alkyl group having 1 to 4 carbon atoms, a fluoroalkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a cyano group or a nitro group, and the carbon atom constituting the divalent aromatic group or the divalent alicyclic alkyl group may be substituted with an oxygen atom, a sulfur atom or a nitrogen atom. At least one of X ¹ and X ² is a 1,4-phenylene group which may have a substituent or a cyclohexane-1,4-diyl group which may have a substituent.] ^Y1 is a single bond or a divalent linking group. n is 1 to 3. When n is 2 or more, a plurality of ^X1s may be the same or different from each other. ^X2 may be the same as or different from any one or all of the plurality of ^X1s . Furthermore, when n is 2 or more, a plurality of ^Y1s may be the same or different from each other. From the viewpoint of liquid crystallinity, n is preferably 2 or more. ^U1 represents a hydrogen atom or a polymerizable group. ^U2 represents a polymerizable group. ^W1 and ^W2 are independently a single bond or a divalent linking group. ^V1 and ^V2 are independently an alkanediyl group having 1 to 20 carbon atoms which may have a substituent, and _-CH2- constituting the alkanediyl group may be substituted with -O-, -CO-, -S- or NH-]

In the polymerizable liquid crystal compound (A-α), ^X1 and ^X2 are preferably independently 1,4-phenylene groups which may have a substituent, or cyclohexane-1,4-diyl groups which may have a substituent, and at least one of ^X1 and ^X2 is 1,4-phenylene groups which may have a substituent, or cyclohexane-1,4-diyl groups which may have a substituent, preferably trans-cyclohexane-1,4-diyl groups. As substituents which may be optionally possessed by the 1,4-phenylene groups which may have a substituent, or the cyclohexane-1,4-diyl groups which may have a substituent, there can be exemplified alkyl groups having 1 to 4 carbon atoms such as methyl, ethyl and butyl groups, cyano groups, and halogen atoms such as chlorine atoms and fluorine atoms. Unsubstituted is preferred.

In terms of easily expressing lamellar liquid crystal properties, the polymerizable liquid crystal compound (A-α) is preferably a polymerizable liquid crystal compound (A-α) in which the part represented by the formula (Aα-1): -(X ¹ -Y ¹ ) _n -X ² - (Aα-1) [wherein X ¹ , Y ¹ , X ² and n each have the same meaning as above] [hereinafter also referred to as partial structure (Aα-1)] is an asymmetric structure. Examples of polymerizable liquid crystal compounds (A-α) having a partial structure (Aα-1) being an asymmetric structure include polymerizable liquid crystal compounds (A-α) in which n is 1 and one X ¹ and one X ² are different from each other. In addition, two polymerizable liquid crystal compounds (A-α) in which n is 2 and two ^Y1s are the same can be exemplified, wherein two ^X1s are the same and one ^X2 is different from the two ^X1s in one structure; and the ^X1 of the two ^X1s bonded to ^W1 is different from the other X1 and ^X2 , and the other ^X1 is the same as ^X2 . Further, a polymerizable liquid crystal compound ( ^A -α) in which n is 3, three ^Y1s are the same, and any one of the three ^X1s and one ^X2 is the same as the other three can be exemplified.

^Y1 is preferably _-CH2CH2- , _-CH2O- , _-CH2CH2O- , _-COO- , _-OCOO- , a single bond, -N=N-, -CRa=CRb-, ^-C≡C- , ^-CRa =N- or -CO- ^NRa- . ^{R a} and R ^b independently represent a hydrogen atom or an ^alkyl group having ₁ to 4 carbon atoms. ^Y1 is more preferably _-CH2CH2- , -COO- or a single bond. When there are plural ^Y1s , the ^Y1 bonded to ^X2 is more preferably _-CH2CH2- or _-CH2O- . When ^X1 and ^X2 are the same structure, it is preferred that there are _two or more ^Y1s with different bonding modes. When there are a plurality of Y1 ^'s with mutually different bonding modes, since an asymmetric structure is formed, there is a tendency to easily exhibit lamellar liquid crystal properties.

U ² is a polymerizable group. U ¹ is a hydrogen atom or a polymerizable group, preferably a polymerizable group. Preferably, U ¹ and U ² are both polymerizable groups, and preferably both are free radical polymerizable groups. As the polymerizable group, the same groups as those exemplified above as the polymerizable groups possessed by the polymerizable liquid crystal compound (A) can be cited. The polymerizable group represented by U ¹ and the polymerizable group represented by U ² may be different from each other, but are preferably the same type of group, preferably at least one of U ¹ and U ² is a (meth)acryl group, and more preferably both are (meth)acryl groups. In addition, the polymerizable group may be in a polymerized state or in an unpolymerized state, preferably in an unpolymerized state.

Examples of the alkanediyl group represented by ^V1 and ^V2 include methylene, ethylidene, propane-1,3-diyl, butane-1,3-diyl, butane-1,4-diyl, pentane-1,5-diyl, hexane-1,6-diyl, heptane-1,7-diyl, octane-1,8-diyl, decane-1,10-diyl, tetradecane-1,14-diyl, and eicosane-1,20-diyl. ^V1 and ^V2 are preferably alkanediyl groups having 2 to 12 carbon atoms, and more preferably alkanediyl groups having 6 to 12 carbon atoms.

Examples of the substituent that the alkanediyl group may optionally have include a cyano group and a halogen atom. The alkanediyl group is preferably unsubstituted, and more preferably an unsubstituted straight-chain alkanediyl group.

^W1 and ^W2 are preferably independently a single bond, -O-, -S-, -COO- or -OCOO-, more preferably a single bond or -O-.

As the polymerizable liquid crystal compound (A), there is no particular limitation as long as it is a polymerizable liquid crystal compound having at least one polymerizable group, and a known polymerizable liquid crystal compound can be used. It is preferably a compound that exhibits lamellar liquid crystal properties. As a structure that easily exhibits lamellar liquid crystal properties, it is preferably a molecular structure that has asymmetry in the molecular structure. Specifically, it is more preferred to have the following partial structures (A-a) to (A-i) and exhibit lamellar liquid crystal properties. From the perspective of easily exhibiting higher-order lamellar liquid crystal properties, it is more preferred to have a partial structure (A-a), (A-b) or (A-c). Furthermore, in the following (A-a) to (A-i), * represents a bond (single bond).

[Chemistry 1]

Specific examples of the polymerizable liquid crystal compound (A) include compounds represented by formula (A-1) to formula (A-25). When the polymerizable liquid crystal compound (A) has a cyclohexane-1,4-diyl group, the cyclohexane-1,4-diyl group is preferably a trans isomer.

[Chemistry 2]

[Chemistry 3]

[Chemistry 4]

[Chemistry 5]

[Chemistry 6]

Among them, at least one selected from the group consisting of compounds represented by formula (A-2), formula (A-3), formula (A-4), formula (A-5), formula (A-6), formula (A-7), formula (A-8), formula (A-13), formula (A-14), formula (A-15), formula (A-16) and formula (A-17) is preferred. As the polymerizable liquid crystal compound (A), one kind may be used alone or two or more kinds may be used in combination.

The polymerizable liquid crystal compound (A) can be produced by a known method described in, for example, Lub et al., Recl. Trav. Chim. Pays-Bas, 115, 321-328 (1996), or Japanese Patent No. 4719156.

In the present invention, the polymerizable liquid crystal composition (A) may also include other polymerizable liquid crystal compounds other than the polymerizable liquid crystal compound (A). From the perspective of obtaining a polarizing element layer with a higher degree of alignment order, the ratio of the polymerizable liquid crystal compound (A) to the total mass of all polymerizable liquid crystal compounds contained in the polymerizable liquid crystal composition (A) is preferably 51 mass % or more, more preferably 70 mass % or more, and further preferably 90 mass % or more.

When the polymerizable liquid crystal composition (A) comprises two or more polymerizable liquid crystal compounds (A), at least one of them may be the polymerizable liquid crystal compound (A1), or all of them may be the polymerizable liquid crystal compound (A-α). By combining a plurality of polymerizable liquid crystal compounds, liquid crystallinity may be temporarily maintained even at a temperature below the liquid crystal-crystalline phase transition temperature.

The content of the polymerizable liquid crystal compound in the polymerizable liquid crystal composition (A) is preferably 40 to 99.9% by weight, more preferably 60 to 99% by weight, and further preferably 70 to 99% by weight relative to the solid content of the polymerizable liquid crystal composition (A). If the content of the polymerizable liquid crystal compound is within the above range, the orientation of the polymerizable liquid crystal compound tends to increase. Furthermore, in this specification, the so-called solid content refers to the total amount of components after removing volatile components such as solvents from the polymerizable liquid crystal composition (A). Hereinafter, in the polymerizable liquid crystal composition for forming a phase difference layer, it also refers to the total amount of components after removing volatile components such as solvents from the composition to be the object.

In the present invention, the polymerizable liquid crystal composition (A) forming the polarizing element layer may include a dichroic dye. Here, the so-called dichroic dye refers to a dye having a property that the absorbance in the long axis direction of the molecule is different from the absorbance in the short axis direction. The dichroic dye that can be used in the present invention is not particularly limited as long as it has the above-mentioned properties, and can be a dye or a pigment. In addition, two or more dyes or pigments can be used in combination, and dyes and pigments can be used in combination. Only one type can be used separately, or two or more types can be used in combination. In addition, the dichroic dye can be polymerizable or liquid crystal.

The dichroic pigment preferably has a maximum absorption wavelength (λ _MAX ) in the range of 300 to 700 nm. Examples of such dichroic pigments include acridine pigments, chrysene pigments, cyanine pigments, naphthalene pigments, azo pigments, and anthraquinone pigments.

Examples of azo dyes include monoazo dyes, disazo dyes, trisazo dyes, tetrakis azo dyes, and stilbene azo dyes, and disazo dyes and trisazo dyes are preferred. For example, compounds represented by formula (I) (hereinafter, also referred to as "compound (I)") can be mentioned. K ¹ (-N=NK ² ) _p -N=NK ³ (I) [In formula (I), K ¹ and K ³ independently represent a phenyl group which may have a substituent, a naphthyl group which may have a substituent, or a monovalent heterocyclic group which may have a substituent. K ² represents a paraphenyl group which may have a substituent, a naphthalene-1,4-diyl group which may have a substituent, or a divalent heterocyclic group which may have a substituent. p represents an integer of 1 to 4. When p is an integer of 2 or more, a plurality of K ^2s may be the same or different from each other. In the range showing absorption in the visible light region, -N=N- bonds can be replaced by -C=C-, -COO-, -NHCO-, -N=CH- bonds]

Examples of the monovalent heterocyclic group include groups obtained by removing one hydrogen atom from heterocyclic compounds such as quinoline, thiazole, benzothiazole, thienothiazole, imidazole, benzimidazole, oxadiazole, and benzoxadiazole. Examples of the divalent heterocyclic group include groups obtained by removing two hydrogen atoms from the above heterocyclic compounds.

As phenyl, naphthyl and monovalent heterocyclic groups in ^K1 and ^K3 , and K The substituents optionally possessed by the phenylene group, naphthalene-1,4-diyl group and the divalent heterocyclic group in ² include: alkyl groups having 1 to 20 carbon atoms, alkyl groups having 1 to 20 carbon atoms and having a polymerizable group, alkenyl groups having 1 to 4 carbon atoms; alkoxy groups having 1 to 20 carbon atoms such as methoxy, ethoxy and butoxy groups; alkoxy groups having 1 to 20 carbon atoms and having a polymerizable group; fluorinated alkyl groups having 1 to 4 carbon atoms such as trifluoromethyl group; cyano group; nitro group; halogen atom; substituted or unsubstituted amino groups such as amino groups, diethylamino groups and pyrrolidinyl groups (the so-called substituted amino groups refer to amino groups having 1 or 2 alkyl groups having 1 to 6 carbon atoms, amino groups having 1 or 2 alkyl groups having 1 to 6 carbon atoms and having a polymerizable group, or amino groups in which two substituted alkyl groups are bonded to each other to form an alkanediyl group having 2 to 8 carbon atoms. The unsubstituted amino group is -NH ₂ ), etc. Examples of the polymerizable group include an acryl group, a methacryl group, an acryloxy group, and a methacryloxy group.

Among the compounds (I), a compound represented by any one of the following formulas (I-1) to (I-8) is preferred. [In formulas (I-1) to (I-8), ^B1 to ^B30 are independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a cyano group, a nitro group, a substituted or unsubstituted amino group (the definitions of the substituted amino group and the unsubstituted amino group are as described above), a chlorine atom or a trifluoromethyl group; n1 to n4 are independently an integer of 0 to 3. When n1 is 2 or more, a plurality of ^B2 may be the same or different from each other, when n2 is 2 or more, a plurality of ^B6 may be the same or different from each other, when n3 is 2 or more, a plurality of ^B9 may be the same or different from each other, when n4 is 2 or more, a plurality of ^B14 may be the same or different from each other]

As the anthraquinone pigment, the compound represented by formula (I-9) is preferred. [In formula (I-9), R ¹ to R ⁸ independently represent a hydrogen atom, -R ^x , -NH ₂ , -NHR ^x , -NR ^x ₂ , -SR ^x or a halogen atom. R ^x represents an alkyl group having 1 to 4 carbon atoms or an aryl group having 6 to 12 carbon atoms]

As the above-mentioned ketone pigment, the compound represented by formula (I-10) is preferred. [In formula (I-10), R ⁹ to R ¹⁵ independently represent a hydrogen atom, -R ^x , -NH ₂ , -NHR ^x , -NR ^x ₂ , -SR ^x or a halogen atom. R ^x represents an alkyl group having 1 to 4 carbon atoms or an aryl group having 6 to 12 carbon atoms]

As the acridine dye, a compound represented by formula (I-11) is preferred. [In formula (I-11), R ¹⁶ to R ²³ independently represent a hydrogen atom, -R ^x , -NH ₂ , -NHR ^x , -NR ^x ₂ , -SR ^x or a halogen atom. R ^x represents an alkyl group having 1 to 4 carbon atoms or an aryl group having 6 to 12 carbon atoms] In formula (I-9), formula (I-10) and formula (I-11), examples of the alkyl group having 1 to 6 carbon atoms for R ^x include methyl, ethyl, propyl, butyl, pentyl and hexyl groups, and examples of the aryl group having 6 to 12 carbon atoms include phenyl, toluyl, xylyl and naphthyl groups.

The above-mentioned anthocyanin pigment is preferably a compound represented by formula (I-12) or a compound represented by formula (I-13). [In formula (I-12), ^D1 and ^D2 independently represent a group represented by any one of formulas (I-12a) to (I-12d). [Chemical 12] n5 represents an integer from 1 to 3] [13] [In formula (I-13), D ³ and D ⁴ independently represent a group represented by any one of formulas (I-13a) to (I-13h). [Chemical 14] n6 represents an integer from 1 to 3]

Among the dichroic pigments, azo pigments have higher linearity and are therefore suitable for making a polarizing element layer with excellent polarization performance. Therefore, in one embodiment of the present invention, the dichroic pigment contained in the polymerizable liquid crystal composition (A) forming the polarizing element layer is preferably an azo pigment.

In the present invention, the weight average molecular weight of the dichroic pigment is usually 300-2000, preferably 400-1000.

In one embodiment of the present invention, the dichroic pigment contained in the polymerizable liquid crystal composition (A) forming the polarizing element layer is preferably hydrophobic. If the dichroic pigment is hydrophobic, the compatibility between the dichroic pigment and the polymerizable liquid crystal compound is improved, and the dichroic pigment and the polymerizable liquid crystal compound form a uniform phase, and a polarizing element layer with a higher degree of alignment order can be obtained. Furthermore, in the present invention, the so-called hydrophobic dichroic pigment refers to a pigment having a solubility of less than 1 g in 100 g of water at 25°C.

The content of the dichroic pigment in the polymerizable liquid crystal composition (A) can be appropriately determined according to the type of dichroic pigment used, and is preferably 0.1 to 50 parts by mass, more preferably 0.1 to 20 parts by mass, and further preferably 0.1 to 12 parts by mass relative to 100 parts by mass of the polymerizable liquid crystal compound. If the content of the dichroic pigment is within the above range, it is not easy to disturb the alignment of the polymerizable liquid crystal compound, and a polarizing element layer with a higher degree of alignment order can be obtained.

In the present invention, the polymerizable liquid crystal composition (A) used to form the polarizing element layer may contain a polymerization initiator. The polymerization initiator is a compound that can initiate the polymerization reaction of the polymerizable liquid crystal compound. From the perspective of being able to initiate the polymerization reaction at a lower temperature, a photopolymerization initiator is preferably used. Specifically, a photopolymerization initiator that can generate active free radicals or acids by the action of light can be cited, among which a photopolymerization initiator that generates free radicals by the action of light is preferred. The polymerization initiator can be used alone or in combination of two or more.

As the photopolymerization initiator, a known photopolymerization initiator can be used. For example, as a photopolymerization initiator that generates active free radicals, there are self-cleaving photopolymerization initiators and hydrogen-absorption photopolymerization initiators. As the self-cleaving photopolymerization initiator, self-cleaving benzoin compounds, acetophenone compounds, hydroxyacetophenone compounds, α-aminoacetophenone compounds, oxime ester compounds, acylphosphine oxide compounds, azo compounds, etc. can be used. In addition, as the hydrogen-absorption photopolymerization initiator, hydrogen-absorption benzophenone compounds, benzoin ether compounds, benzyl ketone compounds, dibenzocycloheptanone compounds, anthraquinone compounds, thiophenone compounds, 9-oxythiophenone compounds can be used. Series compounds, halogenated acetophenone series compounds, dialkoxyacetophenone series compounds, halogenated bisimidazole series compounds, halogenated tribasic series compounds, tribasic series compounds, etc.

As the photopolymerization initiator for generating an acid, iodonium salts and cobalt salts can be used.

Among them, from the viewpoint of preventing the dissolution of the pigment, the reaction at a low temperature is preferred. From the viewpoint of the reaction efficiency at a low temperature, a self-cleaving type photopolymerization initiator is preferred, and acetophenone compounds, hydroxyacetophenone compounds, α-aminoacetophenone compounds, and oxime ester compounds are particularly preferred.

As the photopolymerization initiator, specifically, the following can be cited. Benzoin compounds such as benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether and benzoin isobutyl ether; hydroxyacetophenone compounds such as oligomers of 2-hydroxy-2-methyl-1-phenylpropane-1-one, 1,2-diphenyl-2,2-dimethoxyethane-1-one, 2-hydroxy-2-methyl-1-[4-(2-hydroxyethoxy)phenyl]propane-1-one, 1-hydroxycyclohexylphenyl ketone and 2-hydroxy-2-methyl-1-[4-(1-methylvinyl)phenyl]propane-1-one; 2-methyl-2-oxo-1-[4-(1-methylvinyl)phenyl]propane-1-one; α-aminoacetophenone compounds such as 1,2-octanedione, 1-[4-(phenylthio)-1,2-octanedione-2-(O-benzoyl oxime)], 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazole-3-yl]-ethanone-1-(O-acetyl oxime) and other oxime ester compounds; acyl phosphine oxide compounds such as 2,4,6-trimethylbenzyldiphenylphosphine oxide and bis(2,4,6-trimethylbenzyl)phenylphosphine oxide ; Benzophenone compounds such as benzophenone, methyl o-benzoylbenzoate, 4-phenylbenzophenone, 4-benzoyl-4'-methyldiphenyl sulfide, 3,3',4,4'-tetrakis(tert-butylcarbonylperoxide)benzophenone and 2,4,6-trimethylbenzophenone; Dialkoxyacetophenone compounds such as diethoxyacetophenone; 2,4-bis(trichloromethyl)-6-(4-methoxyphenyl)-1,3,5-tris(2,4-bis(trichloromethyl)-6-(4-methoxynaphthyl)-1,3,5-tris(2,4-bis(trichloromethyl)-6-(4-methoxynaphthyl)-1,3,5-tris(2,4-bis(trichloromethyl)-6-(4-methoxynaphthyl)-1,3,5-tris(2,4-bis(trichloromethyl)-6-(4- tris(iodine-based compounds such as 2,4-bis(trichloromethyl)-6-[2-(5-methylfuran-2-yl)vinyl]-1,3,5-tris(iodine-based compounds such as 2,4-bis(trichloromethyl)-6-[2-(5-methylfuran-2-yl)vinyl]-1,3,5-tris(iodine-based compounds such as 2,4-bis(trichloromethyl)-6-[2-(furan-2-yl)vinyl]-1,3,5-tris(iodine-based compounds such as 2,4-bis(trichloromethyl)-6-[2-(4-diethylamino-2-methylphenyl)vinyl]-1,3,5-tris(iodine-based compounds such as 2,4-bis(trichloromethyl)-6-[2-(3,4-dimethoxyphenyl)vinyl]-1,3,5-tris(iodine-based compounds such as 2,4-bis(trichloromethyl)-6-[2-(3,4-dimethoxyphenyl)vinyl]-1,3,5-tris(iodine-based compounds such as 2,4-bis(trichloromethyl)- The photopolymerization initiator may be appropriately selected from the above-mentioned photopolymerization initiators according to the relationship with the polymerizable liquid crystal compound contained in the polymerizable liquid crystal composition (A).

Furthermore, a commercially available photopolymerization initiator may also be used. Examples of commercially available photopolymerization initiators include: Irgacure (registered trademark) 907, 184, 651, 819, 250, and 369, 379, 127, 754, OXE01, OXE02, and OXE03 (manufactured by BASF); Omnirad BCIM, Esacure 1001M, and Esacure KIP160 (manufactured by IDM Resins B.V.); Seikuol (registered trademark) BZ, Z, and BEE (manufactured by Seiko Chemical Co., Ltd.); Kayacure (registered trademark) BP100 and UVI-6992 (manufactured by Dow Chemical Co., Ltd.); Adeka Optomer SP-152, N-1717, N-1919, SP-170, Adeka arc Luz NCI-831, Adeka arc Luz NCI-930 (manufactured by ADEKA Co., Ltd.); TAZ-A and TAZ-PP (manufactured by Nihon SiberHegner Co., Ltd.); and TAZ-104 (manufactured by Sanwa Chemical Co., Ltd.), etc.

The content of the polymerization initiator in the polymerizable liquid crystal composition (A) is preferably 1 to 10 parts by mass, more preferably 1 to 8 parts by mass, further preferably 2 to 8 parts by mass, and particularly preferably 4 to 8 parts by mass, relative to 100 parts by mass of the polymerizable liquid crystal compound. If the content of the polymerization initiator is within the above range, the polymerization reaction of the polymerizable liquid crystal compound can be carried out without significantly disturbing the alignment of the polymerizable liquid crystal compound.

Furthermore, the polymerization rate of the polymerizable liquid crystal compound in the present invention is preferably 60% or more, more preferably 65% or more, and even more preferably 70% or more, from the perspective of production line contamination or handling during production.

In the present invention, the polymerizable liquid crystal composition (A) used to form the polarizing element layer may also contain a leveling agent. The leveling agent has the function of adjusting the fluidity of the polymerizable liquid crystal composition (A) so that the coating obtained by applying the polymerizable liquid crystal composition (A) is flatter. By including the leveling agent in the polymerizable liquid crystal composition (A), uneven coating is less likely to occur, and a smooth polarizing element layer can be obtained, which is beneficial to improving the appearance and optical properties of the polarizing plate.

As the leveling agent, specifically, there can be mentioned a surfactant, preferably at least one selected from the group consisting of a leveling agent containing a polyacrylate compound as a main component and a leveling agent containing a fluorine atom-containing compound as a main component. The leveling agent can be used alone or in combination of two or more.

Examples of leveling agents containing polyacrylate compounds as main components include BYK-350, BYK-352, BYK-353, BYK-354, BYK-355, BYK-358N, BYK-361N, BYK-380, BYK-381, and BYK-392 (Bick-Chemie, Germany).

Examples of leveling agents containing fluorine atoms as the main component include Megafac (registered trademark) R-08, the same series R-30, the same series R-90, the same series F-410, the same series F-411, the same series F-443, the same series F-445, the same series F-470, the same series F-471, the same series F-477, the same series F-479, the same series F-482, and The same series "F-483" (DIC Corporation); "Surflon (registered trademark) S-381", the same series "S-382", the same series "S-383", the same series "S-393", the same series "SC-101", the same series "SC-105", "KH-40" and "SA-100" (AGC Seimei Chemical Co., Ltd.); "E1830", "E5844" (Daikin Fine Chemicals Laboratories); "Eftop EF301", "Eftop EF303", "Eftop EF351" and "Eftop EF352" (Mitsubishi Materials Corporation).

When the polymerizable liquid crystal composition (A) contains a leveling agent, its content is preferably 0.05 to 5 parts by weight, and more preferably 0.05 to 3 parts by weight, relative to 100 parts by weight of the polymerizable liquid crystal compound. If the content of the leveling agent is within the above range, it is easy to align the polymerizable liquid crystal compound and is not easy to produce unevenness, so that a smoother polarizing element layer can be obtained.

The polymerizable liquid crystal composition (A) may contain other additives other than the leveling agent. Examples of other additives include polymerizable non-liquid crystal compounds, photosensitizers, antioxidants, mold release agents, stabilizers, colorants such as bluing agents, flame retardants, and lubricants. When the polymerizable liquid crystal composition (A) contains other additives, the content of the other additives relative to the solid content of the polymerizable liquid crystal composition (A) is preferably more than 0% and less than 20% by mass, and more preferably more than 0% and less than 10% by mass.

By adding a photosensitizer to the polymerizable liquid crystal composition (A), the polymerization reaction of the polymerizable liquid crystal compound can be further suppressed. Examples of the photosensitizer include thiophene, 9-thiothiophene, etc. ketone compounds (e.g. 2,4-diethyl-9-oxysulfuron , 2-isopropyl-9-oxysulfide anthracene, anthracene containing alkoxy groups (such as dibutoxyanthracene, etc.); anthracene compounds such as phenanthrene and rubrene, etc. The photosensitizer may be used alone or in combination of two or more.

When the polymerizable liquid crystal composition (A) contains a photosensitizer, its content can be appropriately determined according to the types and amounts of the polymerization initiator and the polymerizable liquid crystal compound, and is preferably 0.1 to 30 parts by mass, more preferably 0.5 to 10 parts by mass, and further preferably 0.5 to 8 parts by mass, relative to 100 parts by mass of the polymerizable liquid crystal compound.

The polymerizable liquid crystal composition (A) can be prepared by a previously known method for preparing a composition for forming a polarizing element layer. Usually, it can be prepared by mixing and stirring a polymerizable liquid crystal compound and a dichroic pigment, and optionally a polymerization initiator and the above-mentioned additives. In addition, since the viscosity of a compound that generally exhibits lamellar liquid crystal properties is relatively high, the viscosity can be adjusted by adding a solvent from the viewpoint of improving the coating properties of the polymerizable liquid crystal composition (A) and facilitating the formation of a polarizing element layer.

The solvent used in the polymerizable liquid crystal composition (A) can be appropriately selected according to the solubility of the polymerizable liquid crystal compound and the dichroic dye used. Specifically, for example, alcohol solvents such as water, methanol, ethanol, ethylene glycol, isopropanol, propylene glycol, methyl solvent, butyl solvent, and propylene glycol monomethyl ether; ester solvents such as ethyl acetate, butyl acetate, ethylene glycol methyl ether acetate, γ-butyrolactone, propylene glycol methyl ether acetate, and ethyl lactate; ketone solvents such as acetone, methyl ethyl ketone, cyclopentanone, cyclohexanone, methyl amyl ketone, and methyl isobutyl ketone; aliphatic hydrocarbon solvents such as pentane, hexane, and heptane; aromatic hydrocarbon solvents such as toluene and xylene; nitrile solvents such as acetonitrile; ether solvents such as tetrahydrofuran and dimethoxyethane; and chlorinated hydrocarbon solvents such as chloroform and chlorobenzene. These solvents can be used alone or in combination of two or more. The content of the solvent is preferably 100 to 1900 parts by mass, more preferably 150 to 900 parts by mass, and even more preferably 180 to 600 parts by mass, relative to 100 parts by mass of the solid content of the polymerizable liquid crystal composition (A).

In the present invention, the polarizing element layer is preferably a polarizing element layer with a higher degree of alignment order. A polarizing element layer with a higher degree of alignment order can obtain a Bragg peak originating from a higher-order structure such as a hexagonal phase or a crystalline phase in an X-ray diffraction measurement. The so-called Bragg peak refers to a peak of a planar periodic structure originating from molecular alignment. Therefore, the polarizing element layer constituting the polarizing film of the present invention preferably shows a Bragg peak in an X-ray diffraction measurement. That is, in the polarizing element layer constituting the polarizing film of the present invention, it is preferred that the polymerizable liquid crystal compound or its polymer is oriented in such a way that the polarizing element layer shows a Bragg peak in the X-ray diffraction measurement, and it is more preferred that the polymerizable liquid crystal compound or its polymer is "horizontally aligned", that is, the molecules of the polymerizable liquid crystal compound are aligned along the direction of light absorption. In the present invention, it is preferred that the polarizing element layer has a surface period interval of 3.0 to 6.0 Å for the molecular alignment. A high degree of alignment order such as showing a Bragg peak can be achieved by controlling the type of polymerizable liquid crystal compound used, the type or amount of dichroic pigment, and the type or amount of polymerization initiator, etc.

The polarizing element layer can be obtained, for example, by a method comprising the following steps: forming a coating of a polymerizable liquid crystal composition (A) on a substrate or an alignment film disposed on the substrate; removing the solvent from the coating; causing the polymerizable liquid crystal compound to phase-transfer into a liquid crystal phase (lamellar phase); and polymerizing the polymerizable liquid crystal compound while maintaining the above-mentioned liquid crystal phase.

As a substrate, there is no particular limitation as long as it can support the polarizing element layer or the alignment film when manufacturing the polarizing element layer, and a substrate known in the field can be used. For example, a glass substrate or a resin substrate can be cited. From the perspective of processability, a resin substrate is preferred. The resin substrate is preferably a substrate having light transmittance that allows visible light to pass through. Here, the so-called light transmittance refers to a visibility-corrected single transmittance of 80% or more relative to light in the wavelength range of 380 to 780 nm.

Examples of the resin constituting the resin substrate include polyolefins such as polyethylene, polypropylene, and norbornene polymers; cyclic olefin resins; polyvinyl alcohol; polyethylene terephthalate; polymethacrylate; polyacrylate; cellulose esters such as triacetyl cellulose, diacetyl cellulose, and cellulose acetate propionate; polyethylene naphthalate; polycarbonate; polysulfone; polyethersulfone; polyetherketone; and plastics such as polyphenylene sulfide and polyphenylene ether. Such resins can be made into a substrate by forming a film using a known method such as solvent casting or melt extrusion. The substrate surface may have a protective layer formed of acrylic resin, methacrylic resin, epoxy resin, cyclobutane resin, polyurethane resin, melamine resin, etc., and may also be subjected to surface treatment such as silicone release treatment, corona treatment, plasma treatment, etc.

As the substrate, a commercially available product may be used. Examples of commercially available cellulose ester substrates include cellulose ester substrates manufactured by Fujitac Film Co., Ltd., and cellulose ester substrates such as "KC8UX2M", "KC8UY", and "KC4UY" manufactured by Konica Minolta Opto Co., Ltd. Examples of commercially available cyclic olefin resins include: "Topas (registered trademark)" and other cyclic olefin resins manufactured by Ticona (Germany); "Arton (registered trademark)" and other cyclic olefin resins manufactured by JSR Corporation; "ZEONOR (registered trademark)" and "ZEONEX (registered trademark)" and other cyclic olefin resins manufactured by Zeon Co., Ltd.; and "Apel" (registered trademark) and other cyclic olefin resins manufactured by Mitsui Chemicals, Inc. Such cyclic olefin resins can be made into a resin substrate by forming a film using a known method such as solvent casting or melt extrusion. Commercially available cyclic olefin resin substrates can also be used. Examples of commercially available cyclic olefin resin substrates include: "S-SINA (registered trademark)" and "SCA40 (registered trademark)" manufactured by Sekisui Chemical Industries, Ltd.; "Zeonor Film (registered trademark)" manufactured by Optronics Co., Ltd.; and "Arton Film (registered trademark)" manufactured by JSR Co., Ltd.

The thickness of the substrate is preferably thinner from the perspective of practical operability, and is generally 5 μm to 300 μm, preferably 10 μm to 200 μm from the perspective of strength or processability. In addition, the substrate layer may be provided in a removable manner, for example, after the polarizing element layer of the polarizing film is attached to a component constituting a display device or the phase difference layer described below, it may be removable from the polarizing film.

Examples of methods for coating the polymerizable liquid crystal composition on a substrate include known methods such as spin coating, extrusion coating, gravure coating, die coating, rod coating, and smear coating, and printing methods such as flexographic coating.

Then, under the condition that the polymerizable liquid crystal compound contained in the coating film obtained from the polymerizable liquid crystal composition (A) does not polymerize, the solvent is removed by drying or the like, thereby forming a dry coating film. Examples of the drying method include natural drying, ventilation drying, heating drying, and reduced pressure drying.

Furthermore, in order to make the polymerizable liquid crystal compound phase transition to the liquid phase, the temperature is raised to a temperature above the temperature at which the polymerizable liquid crystal compound phase transitions to the liquid phase and then lowered to make the polymerizable liquid crystal compound phase transition to the liquid crystal phase (stratified phase). The phase transition can be performed after the solvent in the above-mentioned coating is removed, or it can be performed simultaneously with the removal of the solvent.

The polymerizable liquid crystal compound is polymerized while maintaining the liquid crystal state of the polymerizable liquid crystal compound, thereby forming a polarizing element layer as a cured product of the polymerizable liquid crystal composition (A). As a polymerization method, photopolymerization is preferred. In photopolymerization, the light irradiated on the dry coating can be appropriately selected according to the type of polymerizable liquid crystal compound contained in the dry coating (especially the type of polymerizable group possessed by the polymerizable liquid crystal compound), the type of polymerization initiator and the amount thereof. As a specific example, one or more active energy rays or active electron beams selected from the group consisting of visible light, ultraviolet light, infrared light, X-rays, α rays, β rays and γ rays can be cited. Among them, ultraviolet light is preferred from the perspective of easy control of the progress of the polymerization reaction or the wide range of users in the field of photopolymerization devices. It is preferred to preselect the type of polymerizable liquid crystal compound or polymerization initiator contained in the polymerizable liquid crystal composition (A) in a manner that utilizes ultraviolet light for photopolymerization. In addition, during polymerization, the polymerization temperature can be controlled by cooling the dried coating film using an appropriate cooling method while irradiating the film with light. During photopolymerization, a patterned polarizing element layer can also be obtained by shielding or developing.

Examples of the light source of the active energy line include low-pressure mercury lamps, medium-pressure mercury lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, xenon lamps, halogen lamps, carbon arc lamps, tungsten lamps, gallium lamps, excimer lasers, LED light sources emitting light in the wavelength region of 380 to 440 nm, chemical lamps, black light lamps, microwave-excited mercury lamps, and metal halide lamps.

The intensity of ultraviolet irradiation is usually 10 to 3,000 mW/cm ² . The intensity of ultraviolet irradiation is preferably within the wavelength region effective for activating the polymerization initiator. The irradiation time is usually 0.1 second to 10 minutes, preferably 1 second to 5 minutes, more preferably 5 seconds to 3 minutes, and further preferably 10 seconds to 1 minute. If the ultraviolet irradiation intensity is used once or multiple times, the cumulative light amount is 10 to 3,000 mJ/cm ² , preferably 50 to 2,000 mJ/cm ² , and more preferably 100 to 1,000 mJ/cm ² .

By photopolymerization, the polymerizable liquid crystal compound will polymerize while maintaining the liquid crystal phase, especially the smectic phase, preferably the liquid crystal state of the higher order smectic phase, to form a polarizing element layer. The polarizing element layer obtained by polymerizing the polymerizable liquid crystal compound while maintaining the liquid crystal state of the smectic phase is also accompanied by the effect of the above-mentioned dichroic pigment, and has the advantage of higher polarization performance compared with the previous host-guest type polarizing film, that is, the polarizing element layer containing the liquid crystal state of the nematic phase. Furthermore, compared with the one coated with only the dichroic pigment or the hydrotropic liquid crystal, it also has the advantage of excellent strength.

The thickness of the polarizing element layer can be appropriately selected according to the purpose of the polarizing film, and is preferably 0.1 to 5 μm, more preferably 0.3 to 4 μm, and further preferably 0.5 to 3 μm. If the thickness of the polarizing element layer is above the lower limit, it is easy to prevent the situation where the required light absorption cannot be obtained. If it is below the upper limit, when the polarizing element layer is formed on the alignment film, it is easy to suppress the generation of alignment defects caused by the decrease of the alignment restriction force.

When forming the polarizing element layer, by coating the polymerizable liquid crystal composition (A) on the alignment film, it is easy to align the polymerizable liquid crystal compound and the dichroic pigment in the desired direction. The alignment film has an alignment limiting force that aligns the polymerizable liquid crystal compound in the desired direction. As the alignment film, it is preferred to have solvent resistance that will not be dissolved by the organic solvent contained in the polymerizable liquid crystal composition (A), and have heat resistance during the heat treatment for removing the solvent or aligning the polymerizable liquid crystal compound. As the alignment film, there can be cited: an alignment film comprising an alignment polymer, a light alignment film formed by a composition comprising a polymer and a solvent that generates an alignment limiting force using light, a groove alignment film having a concave-convex pattern or a plurality of grooves on the surface, and a stretch film stretched in the alignment direction. From the perspective of being able to easily obtain a high-quality alignment film by controlling the alignment angle with high precision, a photo-alignment film is preferred.

As the alignment polymer, there can be cited: polyamides or gelatins having an amide bond in the molecule, polyimides having an imide bond in the molecule and polyamides as their hydrolyzates, polyvinyl alcohol, alkyl-modified polyvinyl alcohol, polyacrylamide, polyazole, polyethyleneimine, polystyrene, polyvinyl pyrrolidone, polyacrylic acid and polyacrylates. Among them, polyvinyl alcohol is preferred. The alignment polymer can be used alone or in combination of two or more.

The alignment film including the alignment polymer can be generally obtained by applying a composition in which the alignment polymer is dissolved in a solvent (hereinafter, sometimes referred to as "alignment polymer composition") to a substrate and removing the solvent; or applying the alignment polymer composition to a substrate, removing the solvent, and rubbing (rubbing method). Examples of the solvent include the same ones as those exemplified above as organic solvents that can be used in the polymerizable liquid crystal composition (A).

The concentration of the alignment polymer in the alignment polymer composition can be within the range that the alignment polymer material can be completely dissolved in the solvent. It is preferably 0.1 to 20%, more preferably about 0.1 to 10%, calculated as solid content relative to the solution.

As the alignment polymer composition, a commercially available alignment film material may be used directly. Examples of commercially available alignment film materials include Sunever (registered trademark, manufactured by Nissan Chemical Industries, Ltd.) and Optomer (registered trademark, manufactured by JSR Corporation).

As a method for applying the aligning polymer composition on a substrate, the same methods as those exemplified as the method for applying the polymerizable liquid crystal composition (A) on a substrate can be cited.

Examples of methods for removing the solvent contained in the alignment polymer composition include natural drying, ventilation drying, heat drying, and reduced pressure drying.

In order to impart an alignment restricting force to the alignment film, a rubbing treatment (rubbing method) may be performed as necessary.

As a method of imparting an alignment restricting force by rubbing, there can be cited a method of bringing a film of an alignment polymer formed on the surface of a substrate by applying an alignment polymer composition to a substrate and annealing the same into contact with a rubbing roller wound with a rubbing cloth and rotating.

The photo-alignment film can be generally formed by the following method: a composition containing a polymer or monomer having a photoreactive group and generating an alignment restricting force by light, and a solvent (hereinafter also referred to as a "photo-alignment film forming composition") is applied to a substrate or the like to form a coating film, the solvent is dried and removed from the obtained coating film, and then the obtained dried coating film is irradiated with polarized ultraviolet light. The photo-alignment film is more preferable in that the direction of the alignment restricting force can be arbitrarily controlled by selecting the polarization direction of the polarized ultraviolet light irradiated. If the polymer contained in the composition for forming the photo-alignment film has a reactive group (for example, a (meth)acryl group) that is the same as the polymerizable group possessed by the polymerizable liquid crystal compound contained in the polymerizable liquid crystal composition (A), the adhesion between the photo-alignment film and the polarizing element layer tends to be improved. For a polarizing film with a special shape satisfying formula (1), it is more advantageous in suppressing the occurrence of protrusions or peeling of the polarizing element layer.

The so-called photoreactive group refers to a group that generates liquid crystal alignment ability by light irradiation. Specifically, it can be cited as a group that participates in the following photoreactions, which are reactions that become the source of liquid crystal alignment ability by inducing molecular alignment or isomerization reaction, dimerization reaction, photocrosslinking reaction or photodecomposition reaction generated by light irradiation. Among them, from the perspective of excellent alignment, groups that participate in dimerization reaction or photocrosslinking reaction are preferred. The photoreactive group is preferably a group having an unsaturated bond, especially a double bond, and particularly preferably a group having at least one selected from the group consisting of a carbon-carbon double bond (C=C bond), a carbon-nitrogen double bond (C=N bond), a nitrogen-nitrogen double bond (N=N bond) and a carbon-oxygen double bond (C=O bond).

Examples of photoreactive groups having a C=C bond include vinyl, polyene, stilbene, styrylpyridyl, styrylpyridinium, chalcone, and cinnamyl groups. Examples of photoreactive groups having a C=N bond include groups having structures such as aromatic Schiff bases and aromatic hydrazones. Examples of photoreactive groups having an N=N bond include azophenyl, azonaphthyl, aromatic heterocyclic azo, bisazo, formazan, and groups having an azoxybenzene structure. Examples of photoreactive groups having a C=O bond include benzophenone, coumarin, anthraquinone, and cis-butylenediimide groups. These groups may have a substituent such as an alkyl group, an alkoxy group, an aryl group, an allyloxy group, a cyano group, an alkoxycarbonyl group, a hydroxyl group, a sulfonic acid group, or a halogenated alkyl group.

Among them, the photoreactive groups that participate in the photodimerization reaction are preferred. From the perspective of relatively less polarized light irradiation required for photoalignment and the ease of obtaining a photoalignment film with excellent thermal stability or temporal stability, cinnamyl and chalcone groups are preferred. As the polymer having the photoreactive group, a cinnamyl group that makes the terminal of the polymer side chain a cinnamic acid structure is particularly preferred.

The number average molecular weight of the polymer with photoreactive groups that forms the photoalignment film is preferably 20,000 to 100,000, more preferably 22,000 or more, further preferably 25,000 or more, and further preferably 90,000 or less, further preferably 80,000 or less. If the number average molecular weight of the polymer with photoreactive groups is within the above range, the adhesion with the layer adjacent to the photoalignment film can be easily improved, and the substrate and the polarizing element layer can be laminated with good adhesion through the photoalignment film. The number average molecular weight of the polymer with photoreactive groups can be controlled by the amount of monomers used in the photoalignment film forming composition, the type or amount of polymerization initiator, etc. Furthermore, the "number average molecular weight of the polymer having a photoreactive group" mentioned here is substantially equivalent to the number average molecular weight of the polymer constituting the photo-alignment film after curing, and can be calculated by measuring the photo-alignment film itself after curing using a measuring instrument such as a gel permeation chromatograph.

By applying the photo-alignment film-forming composition on, for example, a substrate, a photo-alignment inducing layer can be formed. The solvent contained in the composition may be the same solvent as that exemplified above as the solvent that may be contained in the polymerizable liquid crystal composition (A), and may be appropriately selected according to the solubility of the polymer having a photoreactive group.

The content of the polymer having a photoreactive group in the photo-alignment film-forming composition can be appropriately adjusted according to the type of polymer or the thickness of the target photo-alignment film, and is preferably at least 0.2% by mass, more preferably in the range of 0.3-10% by mass, relative to the mass of the photo-alignment film-forming composition. The photo-alignment film-forming composition may also contain a polymer material or a photosensitizer such as polyvinyl alcohol or polyimide within the range that the properties of the photo-alignment film are not significantly impaired.

As a method for applying the photo-alignment film-forming composition on a substrate and a method for removing the solvent from the applied photo-alignment film-forming composition, the same methods as the method for applying the polymerizable liquid crystal composition (A) on a substrate and the method for removing the solvent from the formed coating film can be cited.

The polarized light irradiation may be in the form of directly irradiating the photo-alignment film-forming composition coated on the substrate after the solvent is removed with polarized UV (ultraviolet light), or in the form of irradiating the polarized light from the substrate side and allowing the polarized light to pass through. In addition, the polarized light is preferably substantially parallel light. The wavelength of the polarized light irradiated is preferably in the wavelength region where the photoreactive group of the polymer having the photoreactive group can absorb the light energy. Specifically, UV with a wavelength range of 250 to 400 nm is particularly preferred. As the light source used for the polarized light irradiation, there can be cited: xenon lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, metal halide lamps, KrF, ArF and other ultraviolet lasers, etc., preferably high-pressure mercury lamps, ultra-high-pressure mercury lamps and metal halide lamps. Among them, high-pressure mercury lamps, ultra-high-pressure mercury lamps and metal halide lamps are preferred because of the greater intensity of ultraviolet light with a wavelength of 313 nm. Polarized UV can be irradiated by passing the light from the above light sources through an appropriate polarizing element. As the polarizing element, a polarizing filter, a polarizing prism such as Glenn-Thompson or Glenn-Taylor, or a wire-grid type polarizing element can be used.

The thickness of the photo-alignment film is preferably 10 to 5000 nm, more preferably 10 to 1000 nm, and further preferably 30 to 300 nm. If the thickness of the photo-alignment film is within the above range, it can exhibit good adhesion to the interface with the polarizing element layer or the interface with the substrate, and exert an alignment restriction force, so that the polarizing element layer can be formed with a higher alignment order.

The polarizing film of the present invention may also include layers other than the substrate, the alignment film, and the polarizing element layer. Such other layers include, for example: a protective layer for the purpose of protecting or reinforcing the polarizing element layer, a hard coating layer, a primer layer, or an adhesive layer.

In the present invention, an elliptical polarizing plate including the polarizing film of the present invention and a phase difference layer having a 1/4 wave plate function is also taken as an object. In the elliptical polarizing plate of the present invention, the phase difference layer may be a layer including a stretched film, preferably a coating layer, and more preferably a cured product of a polymerizable liquid crystal composition including at least one polymerizable liquid crystal compound. If the phase difference layer is a coating layer, it is easy to improve the stacking property with the polarizing film of the present invention having a special shape, and it is easy to become a phase difference layer that can show higher optical characteristics.

In the present invention, the phase difference layer having the function of a quarter wave plate refers to a layer satisfying the following formula (4): 100 nm≤Re(550)≤170 nm        (4) [In formula (4), Re(λ) represents the in-plane phase difference value of the phase difference layer at a wavelength of λ nm]. By satisfying the above formula (4), the phase difference layer functions as a λ/4 plate, and the effect of improving the front reflection hue (the effect of suppressing coloration) when the elliptical polarizing plate including the phase difference layer is applied to an organic EL display device, etc. is easily improved. The more preferable range of the in-plane phase difference value of the phase difference layer is 130 nm≤Re(550)≤150 nm.

Furthermore, the phase difference layer preferably satisfies the following formulas (5) and (6): Re(450)/Re(550)≤1.00       (5) 1.00≤Re(650)/Re(550)       (6) [Wherein, Re(λ) represents the in-plane phase difference value of the phase difference layer at a wavelength of λ nm]. When the phase difference layer satisfies formulas (5) and (6), the phase difference layer exhibits so-called reverse wavelength dispersion, that is, the in-plane phase difference value at a short wavelength is smaller than the in-plane phase difference value at a long wavelength. When an elliptical polarizer having such a phase difference layer is incorporated into an organic EL display device, etc., the front hue tends to be excellent. From the viewpoint of improving the anti-wavelength dispersion and further improving the effect of improving the reflected hue in the front direction of the elliptical polarizer, Re(450)/Re(550) is preferably 0.70 or more, more preferably 0.78 or more, and more preferably 0.92 or less, more preferably 0.90 or less, further preferably 0.87 or less, particularly preferably 0.86 or less, and even more preferably 0.85 or less. Furthermore, Re(650)/Re(550) is preferably 1.01 or more, and more preferably 1.02 or more.

The above-mentioned in-plane phase difference value can be adjusted by the film thickness dA of the phase difference layer. Since the in-plane phase difference value is determined by the above formula ReA(λ)＝(nxA(λ)－nyA(λ))×dA, to obtain the required in-plane phase difference value (ReA(λ): the in-plane phase difference value of the phase difference layer at wavelength λ(nm)), it is only necessary to adjust the three-dimensional refractive index and the film thickness dA.

In the present invention, the polymerizable liquid crystal compound used to form the phase difference layer can be appropriately selected from the polymerizable liquid crystal compounds previously known in the field of phase difference films according to the required optical properties.

A polymerizable liquid crystal compound is a liquid crystal compound having a polymerizable group. As a polymerizable liquid crystal compound, a polymer (cured product) obtained by polymerizing the polymerizable liquid crystal compound in a state where the polymerizable liquid crystal compound is aligned in a specific direction alone can be exemplified as follows: a polymerizable liquid crystal compound showing positive wavelength dispersion and a polymerizable liquid crystal compound showing reverse wavelength dispersion. In the present invention, only one polymerizable liquid crystal compound can be used, or two polymerizable liquid crystal compounds can be mixed and used.

Examples of the polymerizable liquid crystal compound that can form the phase difference layer in the present invention include the polymerizable liquid crystal compounds described in Japanese Patent Application Laid-Open No. 2011-207765.

The phase difference layer can be obtained by the following method: a polymerizable liquid crystal composition for forming a phase difference layer (hereinafter, also referred to as "polymerizable liquid crystal composition (B)") containing a polymerizable liquid crystal compound, a solvent, and optionally, additives such as a polymerization initiator and a leveling agent is applied to a substrate or an alignment film, the coating is dried, and the polymerizable liquid crystal compound in the polymerizable liquid crystal composition (B) is aligned, and then the polymerizable liquid crystal compound is polymerized by light irradiation while maintaining the alignment state. As the solvent, polymerization initiator, and additive constituting the polymerizable liquid crystal composition (B), the same ones as those exemplified above as the solvent, polymerization initiator, and additive that can be used in the polymerizable liquid crystal composition (A) for forming the polarizing element layer can be cited.

From the perspective of being able to easily impart the required alignment restriction force to various curved shapes with high precision, the alignment film used to form the phase difference layer is preferably a photo-alignment film. As the photo-alignment film or the method of forming the phase difference layer on the photo-alignment film, the same photo-alignment film, method and conditions as those exemplified in the method for forming the polarizing element layer can be cited, and it is sufficient to appropriately select according to the required alignment restriction force or the composition of the phase difference layer.

The thickness of the phase difference layer can be appropriately selected according to the display device to which the elliptical polarizing plate of the present invention is applied. From the perspective of adhesion and thin film formation, the thickness is preferably 0.1 to 5 μm, more preferably 0.2 to 4 μm, and further preferably 0.4 to 3 μm.

For example, the elliptical polarizing plate of the present invention can be produced by laminating the polarizing film of the present invention with a phase difference layer having a 1/4 wave plate function via an adhesive layer. When laminating the polarizing film of the present invention and the phase difference layer, it is preferred to laminate them in a manner that the retardation axis (optical axis) of the phase difference layer and the absorption axis of the polarizing element layer are substantially 45°. By laminating in a manner that the retardation axis (optical axis) of the phase difference layer and the absorption axis of the polarizing element layer are substantially 45°, the function of the elliptical polarizing plate can be obtained. Furthermore, the so-called substantially 45° is usually in the range of 45±5°.

The polarizing film and elliptical polarizing plate of the present invention can be used in various display devices such as speedometers and other instrument panels, liquid crystal display devices such as flexible image display devices, or organic EL display devices.

The flexible image display device includes, for example, a multilayer body for a flexible image display device and an organic EL display panel. The multilayer body for a flexible image display device is arranged on the viewing side relative to the organic EL display panel and is configured in a bendable manner. The multilayer body for a flexible image display device may include a window, an elliptical polarizing plate, a touch sensor, etc. As the elliptical polarizing plate, an elliptical polarizing plate including the polarizing film of the present invention may be used. The stacking order is arbitrary, and preferably the stacking is in the order of window, elliptical polarizer, and touch sensor from the side viewed from the outside, or in the order of window, touch sensor, and elliptical polarizer from the side viewed from the outside.

If there is an elliptical polarizing plate on the viewing side of the touch sensor, the pattern of the touch sensor is not easily visible, and the visibility of the displayed image becomes good, which is preferred. Each component can be laminated using adhesives, adhesives, etc. In addition, the laminated body for the flexible image display device can have a light-shielding pattern formed on at least one side of any one of the above-mentioned window, elliptical polarizing plate, and touch sensor.

The window is arranged on the viewing side of the flexible image display device to protect other components from external impact or environmental changes such as temperature and humidity. Previously, glass was used as such a protective layer, but the window in the flexible image display device is not as rigid and hard as glass, but has a flexible property. The above-mentioned window includes a flexible transparent substrate and may also include a hard coating layer on at least one side.

The above-mentioned transparent substrate preferably has a visible light transmittance of more than 70%, and more preferably has a visible light transmittance of more than 80%. As the above-mentioned transparent substrate, any transparent polymer film can be used. Specifically, the film formed by the following polymers can be cited, and the polymer is: polyethylene, polypropylene, polymethylpentene, cycloolefin derivatives and other polyolefins, the cycloolefin derivatives have units containing monomers of norbornene or cycloolefin; diacetyl cellulose, triacetyl cellulose, propylene cellulose and other (modified) celluloses; methyl methacrylate (co)polymers and other acrylics; styrene (co)polymers and other polystyrenes; acrylonitrile-butadiene-styrene copolymers; acrylic acid; Nitrile-styrene copolymers; ethylene-vinyl acetate copolymers; polyvinyl chlorides; polyvinylidene chlorides; polyesters such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polycarbonate, and polyarylate; polyamides such as nylon; polyimides; polyamide imides; polyether imides; polyether sulfones; polysulfones; polyvinyl alcohols; polyvinyl acetals; polyurethanes; epoxy resins, etc.; unstretched uniaxial or biaxially stretched films can be used. The above polymers can be used alone or in combination of two or more. Among them, polyamide film, polyamide imide film or polyimide film, polyester film, olefin film, acrylic film, cellulose film with excellent transparency and heat resistance are preferred. Inorganic particles such as silicon dioxide, organic microparticles, rubber particles, etc. are also preferably dispersed in the polymer film. Furthermore, it may also contain coloring agents such as pigments or dyes, fluorescent whitening agents, dispersants, plasticizers, heat stabilizers, light stabilizers, infrared absorbers, ultraviolet absorbers, antistatic agents, antioxidants, lubricants, solvents, and other formulations.

The thickness of the transparent substrate is preferably 5 to 200 μm, more preferably 20 to 100 μm.

A hard coating layer may be provided on at least one side of the transparent substrate constituting the window. The thickness of the hard coating layer is not particularly limited, and may be, for example, 2 to 100 μm. If the thickness of the hard coating layer is within the above range, sufficient impact resistance, scratch resistance, and bending resistance can be easily ensured.

The hard coating layer can be formed by curing a hard coating forming composition, wherein the hard coating forming composition includes a reactive material that forms a cross-linked structure when irradiated with active energy rays or heat energy, preferably a composition that is cured by active energy rays. The so-called active energy rays are defined as energy rays that can decompose a compound that generates active species to generate active species. Examples of active energy rays include visible light, ultraviolet rays, infrared rays, X-rays, α rays, β rays, γ rays, and electron beams, and ultraviolet rays are particularly preferred.

The hard coat forming composition generally contains at least one compound of a free radical polymerizable compound and a cationic polymerizable compound, and a polymerization initiator. The free radical polymerizable compound, the cationic polymerizable compound, and the polymerization initiator are not particularly limited, and previously known ones can be cited. The hard coat composition can further contain one or more selected from the group consisting of solvents and additives. As long as the solvent can dissolve or disperse the polymerizable compound or the polymerization initiator, it can be used without limitation as a solvent for a composition for forming a hard coat layer in the field of optical films. As the additive, inorganic particles, leveling agents, stabilizers, surfactants, antistatic agents, lubricants, antifouling agents, etc. can be cited.

Touch sensors can be used as input mechanisms. As touch sensors, the industry has proposed various methods such as resistive film method, surface elastic wave method, infrared method, electromagnetic induction method, electrostatic capacitance method, etc. Any method can be used. Among them, the electrostatic capacitance method is preferred. The electrostatic capacitance touch sensor is divided into an active area and an inactive area located in the contour of the above-mentioned active area. The active area corresponds to the area (display part) in the display panel that displays the screen and senses the user's touch. The inactive area corresponds to the area (non-display part) in the display device that does not display the screen. The touch sensor may include: a substrate with flexible characteristics; a sensing pattern formed in an active area of the substrate; and sensing lines formed in an inactive area of the substrate for connecting the sensing pattern to an external driving circuit via a pad.

There is no particular restriction on the flexible substrate, sensing pattern, and sensing lines, and materials that can be applied in the technical field can be selected respectively.

As a substrate having flexible properties, for example, a substrate comprising the same material as the transparent substrate of the above-mentioned window can be used. Regarding the substrate of the touch panel touch sensor, from the perspective of suppressing cracking of the touch panel touch sensor, it is preferred that the toughness is 2,000 MPa% or more, and more preferably the toughness is 2,000 MPa% to 30,000 MPa%. Here, toughness is defined as: the lower area of the curve from the failure point to the stress (MPa)-strain (%) curve (Stress-strain curve) obtained by the tensile test of the polymer material.

The sensing pattern may include a first pattern formed in a first direction and a second pattern formed in a second direction. The first pattern and the second pattern are arranged in different directions. The first pattern and the second pattern are formed on the same layer, and in order to sense the touched point, each pattern must be electrically connected. The first pattern is a form in which each unit pattern is connected to each other through a connector, and the second pattern is a structure in which each unit pattern is separated from each other in an island form, so in order to electrically connect the second pattern, an additional bridge electrode is required. The sensing pattern can apply well-known transparent electrode materials. For example, indium tin oxide (ITO), indium zinc oxide (IZO), zinc oxide (ZnO), indium zinc tin oxide (IZTO), cadmium tin oxide (CTO), PEDOT (poly (3,4-ethylenedioxythiophene)), carbon nanotubes (CNT), graphene, metal wires, etc., which can be used alone or in combination of two or more. Among them, ITO is preferred. The metal used for the metal wire is not particularly limited, and for example, silver, gold, aluminum, copper, iron, nickel, titanium, tellurium, chromium, etc. can be used alone or in combination of two or more.

The bridge electrode may be formed on the upper part of the sensing pattern through an insulating layer. The bridge electrode may be formed on the substrate, and the insulating layer and the sensing pattern may be formed thereon. The bridge electrode may be formed of the same material as the sensing pattern, or may be formed of metals such as molybdenum, silver, aluminum, copper, palladium, gold, platinum, zinc, tin, titanium, or alloys of two or more of these. Since the first pattern and the second pattern must be electrically insulated, an insulating layer is formed between the sensing pattern and the bridge electrode. The insulating layer may be formed only between the joint of the first pattern and the bridge electrode, or may be formed as a layer covering the sensing pattern. In the latter case, the bridge electrode may be connected to the second pattern via a contact hole formed in the insulating layer. Regarding the above-mentioned touch sensor, as a method for appropriately compensating for the difference in transmittance between a patterned area and a non-patterned area where no pattern is formed, specifically, a difference in light transmittance induced by the difference in refractive index in these areas, an optical adjustment layer may be further included between the substrate and the electrode. The above-mentioned optical adjustment layer may include an inorganic insulating substance or an organic insulating substance. The optical adjustment layer can be formed by coating a photocurable composition including a photocurable organic binder and a solvent on a substrate. The photocurable composition can further include inorganic particles. The use of the inorganic particles can increase the refractive index of the optical adjustment layer.

The above-mentioned photocurable organic adhesive may include, for example, a copolymer of monomers such as acrylate monomers, styrene monomers, and carboxylic acid monomers. The above-mentioned photocurable organic adhesive may be, for example, a copolymer of different repeating units such as repeating units containing epoxy groups, acrylate repeating units, and carboxylic acid repeating units. The above-mentioned inorganic particles may include, for example, zirconium oxide particles, titanium oxide particles, and aluminum oxide particles. The above-mentioned photocurable composition may further include additives such as photopolymerization initiators, polymerizable monomers, and curing aids.

Each layer (window, elliptical polarizing plate, touch panel touch sensor) forming the above-mentioned flexible image display device and the film components (linear polarizing plate, λ/4 phase difference plate, etc.) constituting each layer can be formed using an adhesive. As adhesive adhesives, there can be cited: water-based adhesives, organic solvent-based adhesives, solvent-free adhesives, solid adhesives, solvent-dispersible adhesives, moisture-curing adhesives, heat-curing adhesives, anaerobic curing adhesives, active energy ray-curing adhesives, curing agent mixed adhesives, hot melt adhesives, pressure-sensitive adhesives (adhesives), re-wetting adhesives, etc. Among them, water-based solvent-dispersible adhesives, active energy ray-curable adhesives, and tackifiers are preferably used. As these tackifiers, those previously known in the field of optical films can be appropriately selected and used.

The thickness of the adhesive layer can be appropriately adjusted according to the required bonding force, etc., and is usually 0.01 μm to 500 μm, preferably 0.1 μm to 300 μm. When there are multiple adhesive layers on the above-mentioned flexible image display device laminate, the type and thickness of the adhesive constituting each adhesive layer can be the same or different.

The shading pattern can be used as at least a part of the frame or housing of the flexible image display device. The shading pattern is used to conceal the wiring arranged at the edge of the flexible image display device, making it difficult to be seen, thereby improving the visibility of the image. The shading pattern can be a single layer or a multi-layer form. There is no special restriction on the color of the shading pattern, and it has a variety of colors such as black, white, and metallic color. The shading pattern can be formed by a pigment for presenting color, and a polymer such as acrylic resin, ester resin, epoxy resin, polyurethane, and polysilicone. In addition, the shading pattern can be formed by various methods such as printing, lithography, and inkjet. The thickness of the light-shielding pattern can be 1 μm to 100 μm, preferably 2 μm to 50 μm. In addition, the light pattern can also be given a tilted shape in the thickness direction. [Example]

The present invention is described in more detail below with reference to Examples and Comparative Examples. Unless otherwise specified, "%" and "parts" in the Examples and Comparative Examples refer to "% by mass" and "parts by mass".

[Example 1] (1) Preparation of a composition for forming a photo-alignment film Two parts of a polymer (1) having a number average molecular weight of 28,000 represented by the following chemical formula were mixed with 98 parts of o-xylene, and the obtained mixture was stirred at 80°C for 1 hour to obtain a composition for forming an alignment layer.

Polymer (1) [Chemical 15] (wherein Me represents a methyl group)

(2) Preparation of a composition for forming a polarizing element layer The following components were mixed and stirred at 80° C. for 1 hour to obtain a composition for forming a polarizing element layer. The dichroic dye used was an azo dye described in the examples of Japanese Patent Laid-Open No. 2013-101328. ・ 75 parts of a polymerizable liquid crystal compound represented by formula (1-6) [Chemical 16]

・25 parts of the polymerizable liquid crystal compound represented by formula (1-7) [Chemical 17]

・2.8 parts of the following dichroic pigment (1) [Chemical 18]

・2.8 parts of the dichroic pigment (2) shown below [Chemical 19]

・2.8 parts of the dichroic pigment (3) shown below [Chemical 20]

・Polymerization initiator: 2-dimethylamino-2-benzyl-1-(4-[1-[phenoxy]phenyl)butane-1-one (Irgacure 369; manufactured by Ciba Specialty Chemicals)               6 parts ・Leveling agent: Polyacrylate compound (BYK-361N; manufactured by Beck Chemicals)       1.2 parts ・Solvent: Cyclopentanone      250 parts

(3) Preparation of polarizing film 1 A triacetyl cellulose film (KC4UY-TAC manufactured by Konica Minolta, thickness 40 μm; 200 mm×600 mm quadrilateral film) was treated once using a corona treatment device (AGF-B10; manufactured by Kasuga Electric Co., Ltd.) at an output of 0.3 kW and a treatment speed of 3 m/min. The above-mentioned photo-alignment film-forming composition was applied to the surface subjected to the corona treatment using a rod coater, dried at 80°C for 1 minute, and exposed to polarized UV light at a cumulative light dose of 100 mJ/cm2 using a polarizing UV irradiation device (SPOT CURE SP- ⁷ with polarizing element unit; manufactured by Ushio Electric Co., Ltd.) to form a photo-alignment film. The thickness of the obtained photo-alignment film was measured using an elliptical polarimeter M-220 (manufactured by JASCO Corporation) and the result was 100 nm.

The polarizing element layer forming composition was coated on the obtained photo-alignment film using a bar coater, and then dried in a drying oven set at 110° C. for 1 minute.

Thereafter, a high-pressure mercury lamp (Unicure VB-15201BY-A, manufactured by Niuwei Electric Co., Ltd.) was used to irradiate ultraviolet rays (wavelength: 365 nm, cumulative light quantity at wavelength 365 nm: 1000 mJ/cm ² in a nitrogen environment) to form a polarizing element layer of liquid crystal compound and dichroic pigment alignment, and a polarizing film 1 having a substrate layer, an alignment film, and a polarizing element layer in sequence was obtained. It was confirmed that the angle between the absorption axis of the obtained polarizing film 1 and the long side direction of the film was 0°. In the polarizing film 1, the maximum length A1 of the polarizing element layer in the absorption axis direction was equivalent to the length of the long side direction of the polarizing film 1, and its length was 600 mm. Furthermore, the maximum length A2 in the direction orthogonal to the absorption axis direction of the polarizing element layer and in the same plane as A1 is equal to the length of the short side of the polarizing film 1, and is 200 mm. The value of A1/A2 of the polarizing film 1 is 3.

(4) Preparation of a composition for forming a phase difference layer The following polymerizable liquid crystal compound A-1 (86.0 parts), polymerizable liquid crystal compound A-2 (14.0 parts), polyacrylate compound (leveling agent/BYK-361N; manufactured by Beck Chemical Co., Ltd.) (0.12 parts), and 2-dimethylamino-2-benzyl-1-(4-oxo-1-phenyl)butane-1-one (photopolymerization initiator/Irgacure 369; manufactured by Ciba Specialty Chemicals Co., Ltd.) (3.0 parts) were mixed to obtain a polymerizable liquid crystal composition (A1) containing polymerizable liquid crystal compound A-1 and polymerizable liquid crystal compound A-2.

Polymerizable liquid crystal compound A-1: [Chemical 21]

Polymerizable liquid crystal compound A-2: [Chemical 22]

(5) Preparation of phase difference plate A cycloolefin polymer film (COP; ZF-14; manufactured by Japan Zeon Co., Ltd., 200 mm × 600 mm square) was treated once using a corona treatment device (AGF-B10; manufactured by Kasuga Electric Co., Ltd.) at an output of 0.3 kW and a treatment speed of 3 m/min. The above-mentioned photo-alignment film-forming composition used in the formation of the polarizing element layer was applied to the surface subjected to the corona treatment using a rod coater, dried at 80°C for 1 minute, and exposed to polarized UV light at a cumulative light dose of 100 mJ/ ^cm2 using a polarized UV irradiation device (SPOT CURE SP-7 with polarizing element unit; manufactured by Ushio Electric Co., Ltd.) to form a photo-alignment film. The thickness of the obtained photo-alignment film was measured using an elliptical polarimeter M-220 (manufactured by JASCO Corporation) and the result was 100 nm.

Next, the polymerizable liquid crystal composition (A1) containing the polymerizable liquid crystal compound prepared previously was coated on the photo-alignment film using a rod coater and dried at 120°C for 1 minute. Thereafter, a high-pressure mercury lamp (Unicure VB-15201BY-A; manufactured by Ushio Electric Co., Ltd.) was used to irradiate ultraviolet rays (cumulative light quantity at a wavelength of 313 nm in a nitrogen environment: 500 mJ/cm ² ) from the side coated with the polymerizable liquid crystal composition (A1), thereby forming a phase difference plate as a laminate of a phase difference layer and a cycloolefin polymer film. The thickness of the obtained phase difference layer was measured using a laser microscope (LEXT; manufactured by Olympus Co., Ltd.) and the result was 2.3 μm. The phase difference value of the obtained phase difference plate at a wavelength of 550 nm was measured, and the result was Re(550) = 140 nm. In addition, the phase difference values of the obtained phase difference plate at wavelengths of 450 nm and 650 nm were measured, and the results were Re(450)/Re(550) = 0.85 and Re(650)/Re(550) = 1.05. In addition, the phase difference value of the cycloolefin polymer film at a wavelength of 550 nm is approximately 0, so it will not affect the relationship of the phase difference value.

(6) Preparation of elliptical polarizing plate The polarizing element layer side of the polarizing film and the cycloolefin polymer film side of the phase difference plate are bonded together via an adhesive layer having a thickness of 25 μm in such a way that the absorption axis of the polarizing element layer and the retardation axis of the phase difference layer are at 45°.

Heat resistance evaluation: The phase difference layer side of the above-mentioned elliptical polarizing plate was bonded to a glass plate via an adhesive with a thickness of 25 μm and placed under a temperature condition of 90°C. After 500 hours, the polarizing element layer was evaluated as ○ if it did not peel off, and was evaluated as × if it did peel off. The results are shown in Table 1.

Visibility evaluation: The phase difference layer side of the above-mentioned elliptical polarizing plate was bonded to the organic EL display device via an adhesive layer with a thickness of 25 μm. The organic EL display device was set in a manner that the long side direction of the elliptical polarizing plate was horizontal (horizontal direction relative to the viewer's line of sight), and then the display device was viewed through sunglasses at a distance of 2 m. Those that did not hinder visibility were evaluated as ◎, those that were slightly darkened but did not hinder visibility were evaluated as ○, those that were darkened and hindered visibility were evaluated as △, and those that were not visible were evaluated as ×. The results are shown in Table 1.

[Example 2] Except that the size of the triacetyl cellulose film and the cycloolefin polymer film was set to 200 mm × 1000 mm, an elliptical polarizing plate was manufactured in the same manner as in Example 1, and the heat resistance and visibility were evaluated. The results are shown in Table 1. In the obtained polarizing film, the maximum length A1 of the polarizing element layer in the absorption axis direction is equivalent to the length of the long side direction of the polarizing film, which is 1000 mm. In addition, the maximum length A2 of the polarizing element layer in the same plane as A1 and in a direction orthogonal to the above-mentioned absorption axis direction is equivalent to the length of the short side direction of the polarizing film, which is 200 mm. The results are shown in Table 1.

[Example 3] Except that the dimensions of the triacetyl cellulose film and the cycloolefin polymer film were set to 200 mm × 1400 mm, an elliptical polarizing plate was manufactured in the same manner as in Example 1, and the heat resistance and visibility were evaluated. In the obtained polarizing film, the maximum length A1 of the polarizing element layer in the absorption axis direction was equivalent to the length of the long side direction of the polarizing film, which was 1400 mm. In addition, the maximum length A2 of the polarizing element layer in the same plane as A1 and in a direction orthogonal to the above-mentioned absorption axis direction was equivalent to the length of the short side direction of the polarizing film, which was 200 mm. The results are shown in Table 1.

[Example 4] Except that the polarizing film and the phase difference plate were bonded so that the angle between the absorption axis of the polarizing element layer in the polarizing film 1 and the long side direction of the film was 10°, an elliptical polarizing plate was manufactured in the same manner as in Example 1, and the heat resistance and visibility were evaluated. The results are shown in Table 1.

[Example 5] Except that the polarizing film and the phase difference plate were bonded so that the angle between the absorption axis of the polarizing element layer in the polarizing film 1 and the long side direction of the film was 45°, an elliptical polarizing plate was manufactured in the same manner as in Example 1, and the heat resistance and visibility were evaluated. The results are shown in Table 1.

[Example 6] Except that the polarizing film and the phase difference plate were bonded so that the angle between the absorption axis of the polarizing element layer in the polarizing film 1 and the long side direction of the film was 90°, an elliptical polarizing plate was manufactured in the same manner as in Example 1, and the heat resistance and visibility were evaluated. The results are shown in Table 1.

[Comparative Example 1] Except for using the following polarizing film 2 as the polarizing film, an elliptical polarizing plate was produced in the same manner as in Example 1, and the heat resistance and visibility were evaluated. The results are shown in Table 1. (1) Production of polarizing film 2 A 30 μm thick polyvinyl alcohol film (average degree of polymerization of about 2400, saponification degree of 99.9 mol% or more) was uniaxially stretched by about 5 times by dry stretching, and then immersed in pure water at 40°C for 40 seconds while maintaining the stretched state. Thereafter, the film was immersed in a dyeing aqueous solution having a mass ratio of iodine/potassium iodide/water of 0.044/5.7/100 at 28°C for 30 seconds for dyeing treatment. Next, it was immersed in a boric acid aqueous solution with a mass ratio of potassium iodide/boric acid/water of 11.0/6.2/100 at 70°C for 120 seconds. Then, it was washed with pure water at 8°C for 15 seconds, dried at 60°C for 50 seconds under a tension of 300 N, and then dried at 75°C for 20 seconds to obtain a polarizing element layer with a thickness of 12 μm on which iodine was adsorbed and aligned on the polyvinyl alcohol film. A water-based adhesive was injected between the obtained polarizing element layer and the triacetyl cellulose film (KC4UY-TAC manufactured by Konica Minolta, thickness 40 μm), and the layers were bonded using a roller. The obtained laminate was dried at 60°C for 2 minutes while the tension of the obtained laminate was maintained at 430 N/m. A polarizing film 2 having a triacetyl cellulose film as a protective film on one side was obtained. Furthermore, the above-mentioned aqueous adhesive was prepared by adding 3 parts of carboxyl-modified polyvinyl alcohol (KURARAY POVAL KL318; manufactured by Kuraray Co., Ltd.) and 1.5 parts of water-soluble polyamide epoxy resin (Sumirez Resin 650; manufactured by Sumika Chemtex Co., Ltd., an aqueous solution with a solid content concentration of 30%) to 100 parts of water. Thereafter, the polarizing film 2 was cut into a quadrilateral of 200 mm × 600 mm in such a way that the absorption axis of the polarizing element layer and the long side direction of the film were 0°. In the polarizing film 2, the maximum length A1 of the polarizing element layer in the absorption axis direction is equivalent to the length of the long side direction of the polarizing film 2, and its length is 600 mm. In addition, the maximum length A2 in the direction orthogonal to the absorption axis direction of the polarizing element layer in the same plane as A1 is equivalent to the length of the short side direction of the polarizing film 2, and its length is 200 mm.

[Comparative Example 2] Except that the size of the triacetyl cellulose film and the cycloolefin polymer film as the substrate layer was set to 100 mm × 1500 mm, and the light alignment film and the polarizing element layer were formed in such a way that the angle between the absorption axis of the obtained polarizing film and the short side (100 mm) of the film was 0°, an elliptical polarizing plate was prepared in the same manner as in Example 1, and the heat resistance and visibility were evaluated. In the obtained polarizing film, the maximum length A1 of the polarizing element layer in the absorption axis direction was equivalent to the length of the short side direction of the polarizing film, which was 100 mm. The maximum length A2 of the polarizing element layer in the same plane as A1 and in a direction perpendicular to the absorption axis direction corresponds to the length of the long side of the polarizing film, and is 1500 mm. The results are shown in Table 1.

[Table 1] A1/A2 θ (°) θ' (°) Polarizer layer type Heat resistance visibility Embodiment 1 3 18 0 liquid crystal ○ ◎ Embodiment 2 5 11 0 liquid crystal ○ ◎ Embodiment 3 7 8 0 liquid crystal ○ ◎ Embodiment 4 3 8 10 liquid crystal ○ ○ Embodiment 5 3 27 45 liquid crystal ○ △ Embodiment 6 3 72 90 liquid crystal ○ × Comparative example 1 3 18 0 PVA × ◎ Comparative example 2 15 4 0 liquid crystal × ◎

FIG. 1 is a schematic top view showing an example of the polarizing film of the present invention. FIG. 2 is a schematic top view showing an example of the polarizing film of the present invention. FIG. 3 is a schematic top view showing an example of the polarizing film of the present invention. FIG. 4 is a schematic top view showing an example of the polarizing film of the present invention. FIG. 5 is a schematic top view showing an example of the polarizing film of the present invention.

A1: Length

A2: Length

θ: angle

Claims (7)

A polarizing film, which is a single polarizing film including a polarizing element layer, wherein the polarizing element layer is a cured layer of a polymerizable liquid crystal composition comprising at least one polymerizable liquid crystal compound, and the polarizing film satisfies formula (1) and formula (2): 10>A1/A2>2 (1) [In formula (1), A1 represents the maximum length of the polarizing element layer in the absorption axis direction, and A2 represents the maximum length of the polarizing element layer in the same plane as A1 and in a direction orthogonal to the absorption axis direction];

[In formula (2), θ represents the angle between the direction of the maximum straight line distance between two points located on the outer periphery of the polarizing element layer when the straight line distance between the two points is the maximum and the absorption axis direction of the polarizing element layer]. As in claim 1, the polarizing film, wherein the maximum length A1 of the polarizing element layer in the absorption axis direction is greater than 10 cm and less than 200 cm. The polarizing film as claimed in claim 1 or 2 is roughly rectangular. The polarizing film of claim 3 satisfies formula (3):

[In formula (3), θ' represents the angle between the long side direction of the substantially rectangular shape and the absorption axis direction of the polarizing element layer]. An elliptical polarizing plate, comprising: a polarizing film as in any one of claims 1 to 4, and a phase difference layer having a 1/4 wave plate function. A flexible image display device, comprising an elliptical polarizing plate as claimed in claim 5. A flexible image display device as claimed in claim 6, further comprising a window and a touch sensor.